[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman closed 
https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman updated 
https://github.com/llvm/llvm-project/pull/70107

>From 9db10fc83ec3683b1d5b6f8606fc37a83fe224fa Mon Sep 17 00:00:00 2001
From: Aaron Ballman 
Date: Tue, 24 Oct 2023 15:15:15 -0400
Subject: [PATCH 1/4] [C23] Use thread_local semantics

When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes https://github.com/llvm/llvm-project/issues/70068
---
 clang/docs/ReleaseNotes.rst   |  3 +++
 clang/lib/Parse/ParseDecl.cpp | 11 +--
 clang/test/CodeGen/thread_local.c | 27 +++
 clang/test/Sema/thread_local.c| 16 
 4 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/CodeGen/thread_local.c
 create mode 100644 clang/test/Sema/thread_local.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cf3f0c343b4d014..b104c5da97ab124 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -493,6 +493,9 @@ Bug Fixes in This Version
   Fixes (`#65143 `_)
 - Fix crash in formatting the real/imaginary part of a complex lvalue.
   Fixes (`#69218 `_)
+- No longer use C++ ``thread_local`` semantics in C23 when using
+  ``thread_local`` instead of ``_Thread_local``.
+  Fixes (`#70068 `_)
 
 Bug Fixes to Compiler Builtins
 ^^
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 14a28e5a31c57db..43c18090d6ef79c 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -4076,8 +4076,15 @@ void Parser::ParseDeclarationSpecifiers(
 case tok::kw_thread_local:
   if (getLangOpts().C23)
 Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
-  isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS_thread_local, 
Loc,
-   PrevSpec, DiagID);
+  // We map thread_local to _Thread_local in C23 mode so it retains the C
+  // semantics rather than getting the C++ semantics.
+  // FIXME: diagnostics will now show _Thread_local when the user wrote
+  // thread_local in source in C23 mode; we need some general way to
+  // identify which way the user spelled the keyword in source.
+  isInvalid = DS.SetStorageClassSpecThread(
+  getLangOpts().C23 ? DeclSpec::TSCS__Thread_local
+: DeclSpec::TSCS_thread_local,
+  Loc, PrevSpec, DiagID);
   isStorageClass = true;
   break;
 case tok::kw__Thread_local:
diff --git a/clang/test/CodeGen/thread_local.c 
b/clang/test/CodeGen/thread_local.c
new file mode 100644
index 000..2daa43492cbf271
--- /dev/null
+++ b/clang/test/CodeGen/thread_local.c
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %0 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@k)
+// CHECK-NEXT: %1 = load i32, ptr %0, align 4
+// CHECK-NEXT: %2 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@l)
+// CHECK-NEXT: %3 = load i32, ptr %2, align 4
diff --git a/clang/test/Sema/thread_local.c b/clang/test/Sema/thread_local.c
new file mode 100644
index 000..c4a4dd4ceb1cd0d
--- /dev/null
+++ b/clang/test/Sema/thread_local.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c23 %s -verify
+
+// Ensure that thread_local and _Thread_local are synonyms in C23 and both
+// restrict local variables to be explicitly static or extern.
+void func(void) {
+  // FIXME: it would be nice if the diagnostic said 'thread_local' in this 
case.
+  thread_local int i = 12;  // expected-error {{'_Thread_local' variables must 
have global storage}}
+  _Thread_local int j = 13; // expected-error {{'_Thread_local' variables must 
have global storage}}
+
+  static thread_local int k = 14;
+  static _Thread_local int l = 15;
+
+  extern thread_local 

[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

@@ -493,6 +493,9 @@ Bug Fixes in This Version
   Fixes (`#65143 `_)
 - Fix crash in formatting the real/imaginary part of a complex lvalue.
   Fixes (`#69218 `_)
+- No longer use C++ ``thread_local`` semantics in C23 when using

AaronBallman wrote:

It does, thank you for spotting that! I'm going to add another test case from 
that issue when landing this.

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Mariya Podchishchaeva via cfe-commits]

@@ -493,6 +493,9 @@ Bug Fixes in This Version
   Fixes (`#65143 `_)
 - Fix crash in formatting the real/imaginary part of a complex lvalue.
   Fixes (`#69218 `_)
+- No longer use C++ ``thread_local`` semantics in C23 when using

Fznamznon wrote:

Does this patch also help with 
https://github.com/llvm/llvm-project/issues/69167 ?

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Erich Keane via cfe-commits]

https://github.com/erichkeane approved this pull request.


https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %[[K:.+]] = call align 4 ptr @llvm.threadlocal.address.p0(ptr 
align 4 @k)
+// CHECK-NEXT: %{{.+}} = load i32, ptr %[[K]], align 4

AaronBallman wrote:

Okay, I removed those bits.

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman updated 
https://github.com/llvm/llvm-project/pull/70107

>From 9db10fc83ec3683b1d5b6f8606fc37a83fe224fa Mon Sep 17 00:00:00 2001
From: Aaron Ballman 
Date: Tue, 24 Oct 2023 15:15:15 -0400
Subject: [PATCH 1/3] [C23] Use thread_local semantics

When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes https://github.com/llvm/llvm-project/issues/70068
---
 clang/docs/ReleaseNotes.rst   |  3 +++
 clang/lib/Parse/ParseDecl.cpp | 11 +--
 clang/test/CodeGen/thread_local.c | 27 +++
 clang/test/Sema/thread_local.c| 16 
 4 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/CodeGen/thread_local.c
 create mode 100644 clang/test/Sema/thread_local.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cf3f0c343b4d014..b104c5da97ab124 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -493,6 +493,9 @@ Bug Fixes in This Version
   Fixes (`#65143 `_)
 - Fix crash in formatting the real/imaginary part of a complex lvalue.
   Fixes (`#69218 `_)
+- No longer use C++ ``thread_local`` semantics in C23 when using
+  ``thread_local`` instead of ``_Thread_local``.
+  Fixes (`#70068 `_)
 
 Bug Fixes to Compiler Builtins
 ^^
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 14a28e5a31c57db..43c18090d6ef79c 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -4076,8 +4076,15 @@ void Parser::ParseDeclarationSpecifiers(
 case tok::kw_thread_local:
   if (getLangOpts().C23)
 Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
-  isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS_thread_local, 
Loc,
-   PrevSpec, DiagID);
+  // We map thread_local to _Thread_local in C23 mode so it retains the C
+  // semantics rather than getting the C++ semantics.
+  // FIXME: diagnostics will now show _Thread_local when the user wrote
+  // thread_local in source in C23 mode; we need some general way to
+  // identify which way the user spelled the keyword in source.
+  isInvalid = DS.SetStorageClassSpecThread(
+  getLangOpts().C23 ? DeclSpec::TSCS__Thread_local
+: DeclSpec::TSCS_thread_local,
+  Loc, PrevSpec, DiagID);
   isStorageClass = true;
   break;
 case tok::kw__Thread_local:
diff --git a/clang/test/CodeGen/thread_local.c 
b/clang/test/CodeGen/thread_local.c
new file mode 100644
index 000..2daa43492cbf271
--- /dev/null
+++ b/clang/test/CodeGen/thread_local.c
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %0 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@k)
+// CHECK-NEXT: %1 = load i32, ptr %0, align 4
+// CHECK-NEXT: %2 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@l)
+// CHECK-NEXT: %3 = load i32, ptr %2, align 4
diff --git a/clang/test/Sema/thread_local.c b/clang/test/Sema/thread_local.c
new file mode 100644
index 000..c4a4dd4ceb1cd0d
--- /dev/null
+++ b/clang/test/Sema/thread_local.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c23 %s -verify
+
+// Ensure that thread_local and _Thread_local are synonyms in C23 and both
+// restrict local variables to be explicitly static or extern.
+void func(void) {
+  // FIXME: it would be nice if the diagnostic said 'thread_local' in this 
case.
+  thread_local int i = 12;  // expected-error {{'_Thread_local' variables must 
have global storage}}
+  _Thread_local int j = 13; // expected-error {{'_Thread_local' variables must 
have global storage}}
+
+  static thread_local int k = 14;
+  static _Thread_local int l = 15;
+
+  extern thread_local 

[clang] [C23] Use thread_local semantics (PR #70107)

[Erich Keane via cfe-commits]

@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %[[K:.+]] = call align 4 ptr @llvm.threadlocal.address.p0(ptr 
align 4 @k)
+// CHECK-NEXT: %{{.+}} = load i32, ptr %[[K]], align 4

erichkeane wrote:

Probably not worth having anything up to or including the equals sign here, it 
doesn't really add anything.  Same on line 27.

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %0 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@k)

AaronBallman wrote:

Thanks! I always forget that rule. This should be fixed now.

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

@@ -4076,8 +4076,15 @@ void Parser::ParseDeclarationSpecifiers(
 case tok::kw_thread_local:
   if (getLangOpts().C23)
 Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
-  isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS_thread_local, 
Loc,
-   PrevSpec, DiagID);
+  // We map thread_local to _Thread_local in C23 mode so it retains the C
+  // semantics rather than getting the C++ semantics.
+  // FIXME: diagnostics will now show _Thread_local when the user wrote

AaronBallman wrote:

This should be fixed now.

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman updated 
https://github.com/llvm/llvm-project/pull/70107

>From 9db10fc83ec3683b1d5b6f8606fc37a83fe224fa Mon Sep 17 00:00:00 2001
From: Aaron Ballman 
Date: Tue, 24 Oct 2023 15:15:15 -0400
Subject: [PATCH 1/2] [C23] Use thread_local semantics

When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes https://github.com/llvm/llvm-project/issues/70068
---
 clang/docs/ReleaseNotes.rst   |  3 +++
 clang/lib/Parse/ParseDecl.cpp | 11 +--
 clang/test/CodeGen/thread_local.c | 27 +++
 clang/test/Sema/thread_local.c| 16 
 4 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/CodeGen/thread_local.c
 create mode 100644 clang/test/Sema/thread_local.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cf3f0c343b4d014..b104c5da97ab124 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -493,6 +493,9 @@ Bug Fixes in This Version
   Fixes (`#65143 `_)
 - Fix crash in formatting the real/imaginary part of a complex lvalue.
   Fixes (`#69218 `_)
+- No longer use C++ ``thread_local`` semantics in C23 when using
+  ``thread_local`` instead of ``_Thread_local``.
+  Fixes (`#70068 `_)
 
 Bug Fixes to Compiler Builtins
 ^^
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 14a28e5a31c57db..43c18090d6ef79c 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -4076,8 +4076,15 @@ void Parser::ParseDeclarationSpecifiers(
 case tok::kw_thread_local:
   if (getLangOpts().C23)
 Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
-  isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS_thread_local, 
Loc,
-   PrevSpec, DiagID);
+  // We map thread_local to _Thread_local in C23 mode so it retains the C
+  // semantics rather than getting the C++ semantics.
+  // FIXME: diagnostics will now show _Thread_local when the user wrote
+  // thread_local in source in C23 mode; we need some general way to
+  // identify which way the user spelled the keyword in source.
+  isInvalid = DS.SetStorageClassSpecThread(
+  getLangOpts().C23 ? DeclSpec::TSCS__Thread_local
+: DeclSpec::TSCS_thread_local,
+  Loc, PrevSpec, DiagID);
   isStorageClass = true;
   break;
 case tok::kw__Thread_local:
diff --git a/clang/test/CodeGen/thread_local.c 
b/clang/test/CodeGen/thread_local.c
new file mode 100644
index 000..2daa43492cbf271
--- /dev/null
+++ b/clang/test/CodeGen/thread_local.c
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %0 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@k)
+// CHECK-NEXT: %1 = load i32, ptr %0, align 4
+// CHECK-NEXT: %2 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@l)
+// CHECK-NEXT: %3 = load i32, ptr %2, align 4
diff --git a/clang/test/Sema/thread_local.c b/clang/test/Sema/thread_local.c
new file mode 100644
index 000..c4a4dd4ceb1cd0d
--- /dev/null
+++ b/clang/test/Sema/thread_local.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c23 %s -verify
+
+// Ensure that thread_local and _Thread_local are synonyms in C23 and both
+// restrict local variables to be explicitly static or extern.
+void func(void) {
+  // FIXME: it would be nice if the diagnostic said 'thread_local' in this 
case.
+  thread_local int i = 12;  // expected-error {{'_Thread_local' variables must 
have global storage}}
+  _Thread_local int j = 13; // expected-error {{'_Thread_local' variables must 
have global storage}}
+
+  static thread_local int k = 14;
+  static _Thread_local int l = 15;
+
+  extern thread_local 

[clang] [C23] Use thread_local semantics (PR #70107)

[Erich Keane via cfe-commits]

@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %0 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@k)

erichkeane wrote:

for the %0-3 you probably want to do wildcards, since these can sometimes end 
up with 'names' depending on your config.  The rest I think are all ok.

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[via cfe-commits]

@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c23 %s -verify
+
+// Ensure that thread_local and _Thread_local are synonyms in C23 and both
+// restrict local variables to be explicitly static or extern.
+void func(void) {
+  // FIXME: it would be nice if the diagnostic said 'thread_local' in this 
case.
+  thread_local int i = 12;  // expected-error {{'_Thread_local' variables must 
have global storage}}

cor3ntin wrote:

Another solution would be to say 'thread local variables' which is spelling 
agnostic.

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

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https://github.com/cor3ntin commented:

LGTM but I did not review the codegen tests. 

https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[via cfe-commits]

@@ -4076,8 +4076,15 @@ void Parser::ParseDeclarationSpecifiers(
 case tok::kw_thread_local:
   if (getLangOpts().C23)
 Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
-  isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS_thread_local, 
Loc,
-   PrevSpec, DiagID);
+  // We map thread_local to _Thread_local in C23 mode so it retains the C
+  // semantics rather than getting the C++ semantics.
+  // FIXME: diagnostics will now show _Thread_local when the user wrote

cor3ntin wrote:

```suggestion
  // FIXME: diagnostics will show _Thread_local when the user wrote
```


https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

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https://github.com/cor3ntin edited 
https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[via cfe-commits]

llvmbot wrote:




@llvm/pr-subscribers-clang

Author: Aaron Ballman (AaronBallman)


Changes

When implementing thread_local as a keyword in C23, we accidentally started 
using C++11 thread_local semantics when using that keyword instead of using C11 
_Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local instead. 
This doesn't have the best behavior in terms of diagnostics, but it does 
correct the semantic behavior.

Fixes https://github.com/llvm/llvm-project/issues/70068

---
Full diff: https://github.com/llvm/llvm-project/pull/70107.diff


4 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+3) 
- (modified) clang/lib/Parse/ParseDecl.cpp (+9-2) 
- (added) clang/test/CodeGen/thread_local.c (+27) 
- (added) clang/test/Sema/thread_local.c (+16) 


``diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cf3f0c343b4d014..b104c5da97ab124 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -493,6 +493,9 @@ Bug Fixes in This Version
   Fixes (`#65143 `_)
 - Fix crash in formatting the real/imaginary part of a complex lvalue.
   Fixes (`#69218 `_)
+- No longer use C++ ``thread_local`` semantics in C23 when using
+  ``thread_local`` instead of ``_Thread_local``.
+  Fixes (`#70068 `_)
 
 Bug Fixes to Compiler Builtins
 ^^
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 14a28e5a31c57db..43c18090d6ef79c 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -4076,8 +4076,15 @@ void Parser::ParseDeclarationSpecifiers(
 case tok::kw_thread_local:
   if (getLangOpts().C23)
 Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
-  isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS_thread_local, 
Loc,
-   PrevSpec, DiagID);
+  // We map thread_local to _Thread_local in C23 mode so it retains the C
+  // semantics rather than getting the C++ semantics.
+  // FIXME: diagnostics will now show _Thread_local when the user wrote
+  // thread_local in source in C23 mode; we need some general way to
+  // identify which way the user spelled the keyword in source.
+  isInvalid = DS.SetStorageClassSpecThread(
+  getLangOpts().C23 ? DeclSpec::TSCS__Thread_local
+: DeclSpec::TSCS_thread_local,
+  Loc, PrevSpec, DiagID);
   isStorageClass = true;
   break;
 case tok::kw__Thread_local:
diff --git a/clang/test/CodeGen/thread_local.c 
b/clang/test/CodeGen/thread_local.c
new file mode 100644
index 000..2daa43492cbf271
--- /dev/null
+++ b/clang/test/CodeGen/thread_local.c
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %0 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@k)
+// CHECK-NEXT: %1 = load i32, ptr %0, align 4
+// CHECK-NEXT: %2 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@l)
+// CHECK-NEXT: %3 = load i32, ptr %2, align 4
diff --git a/clang/test/Sema/thread_local.c b/clang/test/Sema/thread_local.c
new file mode 100644
index 000..c4a4dd4ceb1cd0d
--- /dev/null
+++ b/clang/test/Sema/thread_local.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c23 %s -verify
+
+// Ensure that thread_local and _Thread_local are synonyms in C23 and both
+// restrict local variables to be explicitly static or extern.
+void func(void) {
+  // FIXME: it would be nice if the diagnostic said 'thread_local' in this 
case.
+  thread_local int i = 12;  // expected-error {{'_Thread_local' variables must 
have global storage}}
+  _Thread_local int j = 13; // expected-error {{'_Thread_local' variables must 
have global storage}}
+
+  static thread_local int k = 14;
+  static _Thread_local int l = 15;
+
+  extern thread_local int m;
+  extern thread_local int n;
+}
+

``




https://github.com/llvm/llvm-project/pull/70107
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[clang] [C23] Use thread_local semantics (PR #70107)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman created 
https://github.com/llvm/llvm-project/pull/70107

When implementing thread_local as a keyword in C23, we accidentally started 
using C++11 thread_local semantics when using that keyword instead of using C11 
_Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local instead. 
This doesn't have the best behavior in terms of diagnostics, but it does 
correct the semantic behavior.

Fixes https://github.com/llvm/llvm-project/issues/70068

>From 9db10fc83ec3683b1d5b6f8606fc37a83fe224fa Mon Sep 17 00:00:00 2001
From: Aaron Ballman 
Date: Tue, 24 Oct 2023 15:15:15 -0400
Subject: [PATCH] [C23] Use thread_local semantics

When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes https://github.com/llvm/llvm-project/issues/70068
---
 clang/docs/ReleaseNotes.rst   |  3 +++
 clang/lib/Parse/ParseDecl.cpp | 11 +--
 clang/test/CodeGen/thread_local.c | 27 +++
 clang/test/Sema/thread_local.c| 16 
 4 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/CodeGen/thread_local.c
 create mode 100644 clang/test/Sema/thread_local.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cf3f0c343b4d014..b104c5da97ab124 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -493,6 +493,9 @@ Bug Fixes in This Version
   Fixes (`#65143 `_)
 - Fix crash in formatting the real/imaginary part of a complex lvalue.
   Fixes (`#69218 `_)
+- No longer use C++ ``thread_local`` semantics in C23 when using
+  ``thread_local`` instead of ``_Thread_local``.
+  Fixes (`#70068 `_)
 
 Bug Fixes to Compiler Builtins
 ^^
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 14a28e5a31c57db..43c18090d6ef79c 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -4076,8 +4076,15 @@ void Parser::ParseDeclarationSpecifiers(
 case tok::kw_thread_local:
   if (getLangOpts().C23)
 Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
-  isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS_thread_local, 
Loc,
-   PrevSpec, DiagID);
+  // We map thread_local to _Thread_local in C23 mode so it retains the C
+  // semantics rather than getting the C++ semantics.
+  // FIXME: diagnostics will now show _Thread_local when the user wrote
+  // thread_local in source in C23 mode; we need some general way to
+  // identify which way the user spelled the keyword in source.
+  isInvalid = DS.SetStorageClassSpecThread(
+  getLangOpts().C23 ? DeclSpec::TSCS__Thread_local
+: DeclSpec::TSCS_thread_local,
+  Loc, PrevSpec, DiagID);
   isStorageClass = true;
   break;
 case tok::kw__Thread_local:
diff --git a/clang/test/CodeGen/thread_local.c 
b/clang/test/CodeGen/thread_local.c
new file mode 100644
index 000..2daa43492cbf271
--- /dev/null
+++ b/clang/test/CodeGen/thread_local.c
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -std=c23 -emit-llvm -o - %s | 
FileCheck %s
+
+// Ensure that thread_local and _Thread_local emit the same codegen. See
+// https://github.com/llvm/llvm-project/issues/70068 for details.
+
+void func(void) {
+  static thread_local int i = 12;
+  static _Thread_local int j = 13;
+
+  extern thread_local int k;
+  extern thread_local int l;
+
+  (void)k;
+  (void)l;
+}
+
+// CHECK:  @func.i = internal thread_local global i32 12, align 4
+// CHECK-NEXT: @func.j = internal thread_local global i32 13, align 4
+// CHECK-NEXT: @k = external thread_local global i32, align 4
+// CHECK-NEXT: @l = external thread_local global i32, align 4
+
+// CHECK:  define dso_local void @func()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %0 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@k)
+// CHECK-NEXT: %1 = load i32, ptr %0, align 4
+// CHECK-NEXT: %2 = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 
@l)
+// CHECK-NEXT: %3 = load i32, ptr %2, align 4
diff --git a/clang/test/Sema/thread_local.c b/clang/test/Sema/thread_local.c
new file mode 100644
index 000..c4a4dd4ceb1cd0d
--- /dev/null
+++ b/clang/test/Sema/thread_local.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c23 %s -verify
+
+// Ensure that thread_local and _Thread_local are synonyms in C23 and both
+// restrict local variables to be explicitly